The field of the invention is switches having a button, plunger, or other actuator that is linearly operable to open and close switch contacts. More specifically, the invention relates to the operation of magnetically operable sealed switches by such actuators.
There are numerous commercially available switches for industrial applications in which an actuator section of the pushbutton or rotary selector type is mounted to a contact block section which contains one or more switch cartridges. The switch cartridges are modular in construction so that various types and combinations of switch contacts can be mounted in them and easily fastened to the actuator section. This interchangeability of the switch cartridges requires not only that their outer shape and dimensions conform to the actuator, but also, that their operating characteristics be compatible. The latter requirement has proven to be particularly challenging when magnetically operated switches are contained within the cartridge because the operating stroke on commercially available actuator sections is relatively short.
As disclosed in U.S. Pat. No. 3,745,493 issued to Richard A. Funke on July 10, 1973, one means for magnetically operating sealed switches with a relatively short stroke is to operate the switches off the end of a high energy ferrite magnet which is moved linearly by the actuator section. The magnetic field generated by the magnet is concentrated at its ends and the pickup and dropout points of the switch can be made compatible with the relatively short, linear stroke of the actuator. Another approach is disclosed in U.S. Pat. No. 3,403,363 issued to J. N. Pearse et al on Sept. 24, 1968 in which reed switches are disposed in a plane perpendicular to the operating axis of the switch and the linear motion of the actuator section is converted to rotary motion by a cam arrangement. The cam arrangement rotates a disc shaped magnet disposed in a plane adjacent the reed switches to operate them in a relatively short stroke.